Ball-grinding mill



Jam 5% 1926.

P. T. LINDHARD. i

BALL GRINDING KILL Filed Sept. 20. 1924 4 Sheets-Sheet 4l wue'nto/z -r@Ww Jan. 5 1926. v 1,568,752

P. T. LINDHARD BALL GRINDING MILL Filed Sept. 20. 1924 4 Sheets-Sheet 2El W mi; l

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Jan'.' 5 1926. f` 1,568,752

, P. T. LINDHARD BALL @Mmmm HILL Filedsept. 2o. 1924 Shana-sheet :s

invento? Jan. 5 1926.

P. T. LINDHARD BALL GRINDING MILL -Filed Sept. 20, 1924 4 Sheets-Sheet 4/NVE/V BY ,Lau/VY, Q1/LU @arm ATTORNEY FE11M Patented Jan. 5, 1926.

UNITED STATES PATENT oFF1cE.

POVL T. LINDHARD, 0F BROOKLYN. NEW YORK, ASSIGNOR TO F. L. SMIDTI-I &CO., 0F

` NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

BALL-GRINDING MILL.

Application led September 20, 1924. Serial' lNo. 738,767. l

To all whom, it may concern:

Be it known that I, Povr. T. LINDnAun, a citizen of the United States,residing in the borough of Brooklyn, of the city of New York, in theState of New York, have invented certain new and useful Improvements inBall-Grinding Mills, of which the following is a'specification,reference being had to the accompanying drawings, forming a part hereof.

This invention relates to ball grinding mills of the general type ofthose shown in Letters Patent of the United States No. 694,874, March11, 1902, No. 737,750, September 1, '1903, and No. 740,879, October G,1903, which have screeningdevices comh bined with the grinding drum andare arranged for continuous feed of `the material operated upon andcontinuous discharge of the screened material,` while the tailings arereturnd from the screens to the drum for regrinding. In the operation ofsuch machines the screens are subjected to severe wear and it isnecessary to remove and 'replace them from" time to time. Heretofore thescreens have been so mounted as to require considerable time in theirremoval and replacement. One object of the invention is to improve theconstruction so as to require less time and labor in the removal andreplacement of the screens. Heretofore, also, the provision for thereturn of the tailings yfrom the screens to the grinding drum has beensuch that the tailings from one screen must pass the discharge end ofanother screen before reaching the grinding drum so that the freedischarge of the tailings from some of the screens is interfered with bythe .passage through the common conductor of the tailings from otherscreens and it is therefore another object of the invention to overcomethis difficulty. Still another object of the invention has been toconstruct Athe mill in such manner that the screens can be reversed withrespect to the grinding drum so that the drum can be rotated in onedirection or in the other as may bevmost convenient. Other features ofimprovement will be referred to more particularly hereinafter. In thedrawings, in whichris illustra-ted a grinding mill which embodies theseveral features of the present invention- Figure- 1 is a view of the.improved machine in longitudinal, sectional elevation.

Figure2, as to the right hand half, is a view in elevation, as seen fromthe right hand in Figure 1, with the supporting shaft and the dustcasing in section and, as to the left hand half, an elevation as seenfrom the left hand in Figure 1, also with the casing and the shaft insection.

Figure 3 is a view in longitudinal section showing one of the conicalscreens and the means at one end for supporting it in position withrespect to the grinding drum, a portion of which is also shown, thescale of this figure being larger than that of Figures l and 2.

Figure 4 is a view partly in elevation of the parts shown in Figure 3,as seen from the left hand, and partly in section on the plane indicatedby thebroken line 4-4 of Figure 3.

Figures 5 and 6 are detail views in sectional elevation and section, ondifferent planes which are radial with respect to the axis of themachine, showing details of construction of the devices by which eachconical screen is supported in its smaller end.

Figures 7 and 8 are detail views of some of the devices shown in Figures5 and 6, in eleiation, looking toward the axis of the mil v Figure 9 isa view in section on a plane at right angles to the axis of the mill,through the parts through which the tailings are returned from the threescreens of one group to the grinding drum.

Figure 10 is a detail view in section of parts shown in Figure 3.

Figures 11, 12 and 13 are detail views in section on the planesindicated by the broken lines l1-11, 12-12 and 13--13 of Figures 2 and9. i

Figure 14 is a detail view in elevation of some of the parts shown inFigure 11 with the securing bolt in section.

lIn the improved mill illustrated in the drawings as an embodiment ofthe invention, the shaft a is mounted in suitable bearings a', receivesat one end the Wheel a2 through which the mill is driven and supports,through hubs b and b', the end Walls b2, b3 and the circumferential Wallbi of the grinding drum, which is provided as usual with suitableliners. A dust lcasing o encloses` the grinding drum, together w1th the.screens and accessories hereinafter ref ferred to, and is provided with'a discharge opening, as at c, through which the screened materialreceived from the screens- 1s discharged. At one end of the casing 1s afeed hopper (Z which delivers materlal through the hub b into thegrinding drum to'be acted upon therein by the usual grinding bodieswhich are not shown. At theopposite end of the grinding drum, near itsperiphery, is an annular grating e through which the material which hasbeen acted upon by the rinding bodies is discharged into an annu arspace e', within the end wall b of the drum and thence, as will bedescribed, into the smaller ends of the conical screens f which aremounted in a circumferential series about the periphery` of the grindingdrum.

The annular flange g has secured thereto by bolts jg a circumferentialseries of trou h-like castings or saddle pieces h Whic are also boltedtogether, end to end, as at VL', there being one such troughlike castingfor each screen. Each casting or saddle-piece is formed as shown with acentral deilecting surface by which the material received from the drumis dellected into the screen from either side accordin to the directionin which the mill is rotate Each casting, which is symmetrical Withrespect to the axis of the corresponding conical screen, has a cap piecei which is held to the casting la. by a bolt z", the head of which fitsinto a recess h2 in the casting h. The cap piece is provided withhandles 2 to facilitate its removal. The casting and the cap piece areformed to receive a ring f which is itted upon the smaller end of thescreen f, the cap piece being shouldered at i so that when it is inposition' there can be substantially no longitudinal movement of thering f and the screen f toward the casting, but when the cap piece isremoved, the ring f', with the screen f, can be moved further into thecasting, in the space indicated at h3, for a purpose to be referred tohereinafter.

In the operation of the mill the material which passes through thegrating e into the annular space e, asses thence through openings g2 inthe ange piece g and into the space It* Within the casting L and thence,through an opening h5 in the casting, continued also into the cap piece,into the open end of the screen f. It will be noted that the rib orflange h of the casting It serves to prevent the material in the conicalscreen f from Working back into the grinding drum as each screen passesthrough the upper arc of its travel.

The larger end of each conical screen f is received in a ring f2 whichhas a coned seat at f3 in a casting lc, the ring f2 being held in placeby bolts 7'1, which insure the proper setting of the ring f2 in thecasting t,

Each screen can therefore be removed by taking out the two bolts f" atthe larger end and the single bolt e" at the smaller end, removing thecap piece z', and then moving the screen endwise so as to free the ringf2 from its seat in the casting Ic. The correct placing of the cap piecei With respect to the casting h is assured by dowel pins, the positionof which is indicated at f1.7 in Figure 8;

Each hollow casting is formed with a lug s which receives in onedirection one of the bolts 7"* above mentioned and at right anglesthereto a bolt Zr by which it is secured in place.

It will be observed that each hollow casting k is symmetrical withrespect to its major axis so that it can be turned about the axis of thescreen f from the position shown at the left hand in Figure 2 to theopposite position. The purpose is to permit the parts to be assembledfor rotation of the mill either in a right hand direction or in a lefthand direction as the convenience of the user may dictate, withoutrequiring the provision of special castings. The parts through which thetailings are conducted from each hollow casting c back to the inside ofthe grinding drum b2, b, b4 are also formed so that they can be reversedin position according to the direction of rotation of the mill withoutrequiring the provision ol' special castings. Again, the parts are soconstructed and arranged that the tailings from a group of three screensf are returned to the grinding drum through a common collecting tube orconduit which is made up of four sections, the ilrst two of which areidentical and reversible, six such sections being required for a millhaving nine screens, as in the construction illustrated, while the thirdand fourth are also reversible, three of each being required in a millhaving nine screens. Furthermore all parts of the collecting andconducting means are located within the circle of the screens so thatthe destructive eflect of centrifugal action is reduced as compared witha construction in which the collecting tubes are outside of the circleof the screens, and so that the return of the tailings from each screento the grinding drum is interfered with to a much less extent than wouldbe thel case if the tailings were discharged into a collecting tubeoutside oi the circle of the screens. By the improved arrangement, also,the aggregate weight ol' the parts is much reduced.

The collecting and return conduit for each group of three screenscomprises four parts Z, m, a and 0. The parts Z and m, as above stated,are identical, each comprising a collecting tube Z', m', flanged at itsends and a connecting tube Z2 m2, which is flanged at one end forconnection t0 ,the flanged end ofthe hollow casting la and serves todeliver the tailings from such casting into the connecting tube sectionZ or m. The part nv comprises a collecting tube section n', flan fed atits ends, and al connecting section n2 lbanged for connection to thethird castin le of the group and serving to deliver the tailings fromthe corresponding screen to `the collecting tube section a. The sectionn also has a web` bracket n3 with a transverse plate n, to which thecorresponding end of the next collecting tube section Z is secured. Thetube sections Z and m are curved upon a common radius so as to directlthe material toward the axis of the drum. The fourth section o, alsoreversible, is flanged ^at one end for connection to the tube sectiona1. and at its other end is fitted into a radial opening b5 in the hub bof the grinding drum, which opening is deflected, as shown in Figure l,so as to deliver the tailings into the interior of the drum.

Each part /c is secured by the bolt k2, above mentioned, to theconnecting tube Z2, m2 or n2, between it and the axls of the drum, andeach rof the sections Z, fm., n. is secured by a single bolt 79 to theannular angle piece b which unites the adjacent end wall b2 and thecircumferential wall b4 of the grinding drum, as shown particularly inFigure 11. As shown, the bolt p passes through an eccentric bushing p inwhich its angular head p2 is seated. The eccentric p', rotatable by theapplication of a wrench applied to the head p2 of the bolt, is seatedina bearing block p3 which is secured by bolts p4 to a bracket p5riveted to the end of the grinding drum. The other end of the bolt isreceived in a shouldered ring p and receives a `nut p7 at the outside ofthe corresponding section of the collecting and conducting means. Theeccentric p performs no special function in the operation lof the millbut serves a convenient purpose in assembling the several parts of thecollecting and conducting tube as it permits adjustment of the parts toeach other Without requiring accurate ymachining of such parts.

The several details of improved construction above described may or maynot be incorporated in the same mill although they have been designedfor mutual coaction with a view to reduction in the cost of constructionof the mill' as a whole, the adaptation of the mill for rotation in onedirection or the other as may suit the convenience of the user, facilityin the removal and replace- .ment of the screens, and increase in theeficiency of operation ofthe mill as a Whole.

It will be understood that various changes can be made in details ofconstruction `and arrangement to suit the .convenience of the`manufacturer and the requirements of the user and that, except aspointed out in the claims, the intention is not limited to the preciseconstruction shown and described i herein.

I claim as m invention: 4

v 1. In'a grin ing mill, the combination of agrindmg drum, a series oftubular screens dlsposed about the periphery of the grindmg drum andsupported thereby to revolve therewlth, means to deliver ground materialfrom the drum to the screens at one end thereof, and means at the otherend of the screens to return the tailings from the screens to the drum,such means includc ing a common collecting tube for a group of screens,a connection from each screen of the grou) to the collecting tube and aconnection rom the collecting tube to thc y interior of the drum.

2. In a grinding mill, the combination of a grinding drum, a series oftubular screens disposed about the periphery of the grinding drum andsupported thereby to revolve therewith, means to deliver ground materialfrom the drum to the screens at one end thereof, and means at the otherend of the screens to return the tailings from the screens to the drum,such means including a common collecting tube for a group of screens, aconnection from each screen of the group to the collecting tube and aconnection from the collecting tube to the interior of the drum, all ofsaid collecting and connecting means being located withinthe circle ofthe screens.

3. In a grinding mill the combination of va grinding drum, a tubularscreen supportthe position of the hollow casting.

4. In a grinding mill the combination of a grinding drum, a series ofvscreens disposed about the periphery of the grinding drum and supportedthereby to revolve therewith, means including a hollow casting tosupport each screen at one end and receive the tailings therefrom, acommon collecting tube for a group of screens, a connection from eachscreen of the group to the collecting tube, and a connection from thecollecting tube to the `interior of the grinding drum. L

5. In a grinding mill the combination of a grinding drum, a series ofscreens disposed about the periphery of the grinding tube comprisingthree sections secured together and each having a connection to thecorresponding hollow casting, and a connection from the collecting tubeto the drum.

6. In a grinding null the combination of a grinding drum, a tubularscreen supported by the drum to revolve therewith, a hollow casting tosupport the screen at one end and receive the tailings therefrom, acollecting tube section with a connection to the hollow casting, aconnection from the collecting tube to the interior of the grindingdrum, and adjustable means to secure the collecting tube section to thegrinding drum, such means comprising a bearing en bracket secured to thedrum, an eccentric rotatably mounted in the bearing, and a bolt tosecure said section to said eccentric.

7. In a grinding mill the combination of a grinding drum, a series oftubular screens disposed about the periphery of the grinding drum andsupported thereby to revolve therewith,a series of hollow saddle piecessecured to the druml and communicating therewith and supporting thescreens at one end, each of said hollow saddle pieces having a centraldeflector to deflect into the screen material received from the drumfrom either direction, and means to secure the screen to the hollowsaddle piece.

8. In a grinding mill the combination of a grinding drum, a hollowsaddle piece secured to the drum and communicating therewith at eachend, said saddle piece having a central deflecting surface, a tubularscreen supported at one end by the saddle piece and means to secure thetubular screen to the saddle piece.

9. In a grinding mill the combination of a grinding drum, a hollowsaddle piece secured to the drum and communicating therewith at eachend, said saddle piece having a central defiecting surface, a tubular'screen supported at one end by the saddle piece, a cap piece to securethe screen to the saddle piece, and a bolt to secure the cap piece tothe saddle piece.

10. In. a grinding mill the combination of a grindingr drum, a hollowsaddle piece secured to the drum and communicating therewith at one end,said saddle piece having a central deecting surface, a tubular screensupported at one end by the saddle piece, a ring to receive the end ofthe screen and to be received in the saddle piece with capacity forlongitudinal movement, removable means to hold the ring in place in thesaddle piece, and means at the other end of the screen to support thesame on the drum, such means comprising a hollow casting, a ring toreceive the end of the screen and seated on the casting, and means tosecure thering to the casting.

1l. In a grinding mill the combination of a grinding drum, a tubularscreen supported thereby to revolve therewith, a saddle piece andremovable cap piece to support the screen at one end, and a hollowcasting and removable ring to support the screen at the other end.

This specification signed this 13th day of September A. D. 1924.

POVL T. LINDHARD.

